Area Forecast Discussion
Issued by NWS Key West, FL
Issued by NWS Key West, FL
593 FXUS62 KKEY 131734 AFDKEY Area Forecast Discussion National Weather Service Key West FL 134 PM EDT Thu Aug 13 2026 ...New DISCUSSION, MARINE, AVIATION... .KEY MESSAGES... - A Coastal Flood Statement remains in effect for the Lower and Middle Keys, with minor saltwater flooding possible. - A cloud line will be responsible for showers along the Lower Keys through this evening. Additional shower/storm activity will continue into the evening as activity spills off the Mainland. - The best chances for measurable rainfall will be Friday through Saturday evening, before a swath of dry air progresses towards the Keys for late weekend and early next week. && .AVIATION... (18Z TAFS) Issued at 132 PM EDT Thu Aug 13 2026 VFR conditions are expected to persist at both EYW and MTH terminals through the TAF period. Near surface winds will remain mainly southeasterly this afternoon before shifting to the northeast to east this evening and then back to the east to southeast overnight into Friday morning. A cloud line continues along the Lower Keys with the potential for showers continuing for the next few hours. Later this evening, the cloud line is expected to wane, however, convection on the mainland is anticipated to spill southwestward which may bring a shower with some gusty winds to especially MTH. This window is expected to be brief mainly between 13/22z and 14/01z. && .PREV DISCUSSION... Issued at 400 AM EDT Thu Aug 13 2026 As hypothesized when writing this discussion last evening, despite substantial dry air above 850 mb throughout the day today, it is always humbling to remember it is mid-August in the Florida Keys. Light winds supported broken island cloud line formation across the Lower and Middle Keys, although the aforementioned dry air largely stinted associated shower activity. Scattered strong convection developed across the South Florida Mainland, then propagated southwestward in the late evening hours towards the Florida Keys marine zones, before later interacting with a residual lurking ghost boundary north of the Lower and Middle Keys. Since then, the isolated to scattered activity has waned, leaving the entire CWA free of meteorological echo returns. Outside of briefly rain- cooled locations between Big Pine and Marathon, temperatures are generally in the lower to mid 80s at this early morning hour for all land- based surface observation locations. For today, KBYX radar continues to detect residual ghost boundaries lurking throughout the marine zones. Forecast soundings indicate very little change to the synoptic setup, with weak mean northeasterly steering flow likely supportive of additional cloud line formation this afternoon. There is at least some convective allowing model (CAM) support for convective development over South Florida progressing southwestward tomorrow evening. Given the aforementioned lurking boundaries and the convective evolution on Wednesday (a persistence forecast), elected to nudge PoPs upward a bit (around 20%) for both this afternoon and tonight. Beyond today, high pressure will once again strengthen in the North Atlantic over the next several days, supporting modestly freshening easterly breezes. A tropical wave in the vicinity of Puerto Rico will propagate westward towards the Straits of Florida over the next several days, supplying associated boundary layer moistening and cyclonic vorticity support for convection. A late season undulation of Saharan dust will trail the wave. As these two features interact, there will be an elevated chance for rain and thunder, first as the wave approaches the Keys, then again as the Saharan dust takes dominance over the Keys. Timing these windows of elevated rain and thunder chances will be left to the next several forecast cycles, lying somewhere between Friday afternoon and Saturday evening. Global deterministic and ensemble numerical weather prediction guidance diverges a bit for late weekend through early next week. Although the Saharan, dry environment looks to stay for quite some time, a weak frontal boundary may stall somewhere to the north of the Keys. For now, will yield to slightly below normal rain chances, although this will be monitored, depending on the stalling frontal evolution. In terms of the tropics, although the National Hurricane Center is monitoring two possible areas in the Main Development Region of the Tropical Atlantic, neither system is expected to provide impacts to the Keys at this time. && .MARINE... Issued at 1037 AM EDT Thu Aug 13 2026 A Coastal Flood Statement remains in effect for the Lower and Middle Keys, with minor saltwater flooding possible around the time of high tide late this morning through the early afternoon hours. Boaters can expect less clearance under fixed bridges, especially around the time of the high tide. From synopsis, a high pressure system in the central North Atlantic will continue to slide eastward and weaken this afternoon. Gentle east to southeast breezes will slacken, becoming light and variable this afternoon before becoming northeast to east this evening. As the high restrengthens and builds westward, breezes will somewhat freshen for Friday through the weekend. A weak frontal boundary will approach the Florida Peninsula early next week, allowing breezes to slacken once again, becoming light and variable at times. && .PRELIMINARY POINT TEMPS/POPS... Key West 92 83 92 81 / 20 20 30 40 Marathon 90 83 90 82 / 20 20 30 40 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...MJV Aviation/Nowcasts....MJV Data Acquisition.....MJV Visit us on the web at weather.gov/key Follow us on Facebook and X at: www.facebook.com/nwskeywest www.x.com/nwskeywest